1. Field of the Invention
This invention relates to improvements in tamper-evident bands such as those commonly used on bottle caps and, more particularly, to an improved detachable tamper-evidencing band design for improving mounting of the closure on a spout or neck of a container, as well as to improve the grip of the band on the spout.
2. Related Art
U.S. Pat. No. 4,801,031 discloses a tamper-indicating closure that includes an inwardly folded tamper-indicating band with intermittent pleats, around the inwardly folded portion of the band. The pleats are inwardly directed and spaced around the circumference of the band. U.S. Pat. No. 5,400,913 discloses a similar tamper-indicating closure that also has an inwardly folded tamper-indicating band with continuous pleats around the inwardly folded portion of the band.
As discussed in the '913 patent, the tamper-indicating band should slip over the locking bead or rim of the container neck without damaging the frangible web connecting the band to the skirt of the closure. The tamper-indicating band must be sufficiently elastic in order to avoid too great a resistance when closing the bottle, which could damage the frangible web. However, the tamper-indicating band should be sufficiently stiff in order to reliably engage the locking bead of the container neck and thereby hold the band beneath the locking bead when opening the closure, so that the tamper-indicating band will tear at the frangible web.
The '913 patent improves the flexibility of the inwardly folded pleated portion of the band in two ways. One, a frangible web is provided between each pleat. The frangible webs between the pleats ensure high elasticity of the tamper-indicating band during closure. Alternatively, individual bridges, instead of a frangible web, are provided between the pleats. The bridges are relatively easily damaged during opening of the closure, thus improving the tamper-indicating nature of the closure.
It has been determined by the applicant herein that the inwardly-turned pleated designs of both the '031 and '913 patents have a tendency to improperly grip the locking bead of the container neck and, thereby allow the tamper-indicating band to slip back upwardly over the locking bead upon opening of the closure, which defeats the tamper-indicating aspect of the designs. The present invention improves upon this aspect of prior art pleated tamper-indicating bands.
It is also known for the internal thread pattern of a bottle cap to include uniformly spaced gaps around the spiral thread bead for the purpose of reducing weight of the bottle cap as well as to simplify tooling production required to manufacture the bottle caps. The present invention also provides an improved spiral thread pattern and design.